The present invention relates to a method of preparing 2-chloro-pyridinemethanol which is represented by the following formula (1) and is useful as a raw material of medicines and agricultural chemicals. ##STR2## For example, 2-chloro-pyridinemethanol represented by the formula (1) is known as an intermediate for preparing an anti-peptic ulcer agent (see JP-A-58-170779 and JP-A-1-230556) and as an intermediate for preparing an insecticide (see JP-A-61-12682 ) .
Hitherto, there have been some proposed methods of preparing 2-chloro-pyridinemethanol represented by the formula (1). Of these, for example, there is provided a method in which 2-chloro-pyridinemethanol is produced by reducing 2-chloro-(iso)nicotinic acid or its ester with sodium boron hydride (see JP-A-1-230556 and U.S. Pat. No. 4,576,629). However, this method has a problem that diborane and hydrogen which have the risk of explosion are produced. There is provided another method in which 2-chloro-4-pyridinemethanol is produced by hydrogenating 2-chloro-4-cyanopyridine in the presence of a catalyst for hydrogenolysis (see JP-A-4-243867). However, this method has problems that a large amount of 2-chloro-4-aminomethylpyridine as a by-product is produced and that chlorine of the pyridine nucleus is released in the reaction. There is provided still another method in which 2-chloro-4-methylpyridine-N-oxide is reacted with acetic anhydride so as to form 2-chloro-4-acetoxymethylpyridine and then this acetoxymethylpyridine is hydrolyzed so as to form 2-chloro-pyridinemethanol (see Hamana et al. (Journal of the Pharmaceutical Society of Japan written in Japanese) Vol. 81, pp. 574-578 (1961), cf. Chemical Abstracts, vol. 55, no. 24, 2473f, (1961). However, this method has a problem that a large amount of by-product in the form of tar is produced by the reaction between 2-chloro-4-methyl-pyridine-N-oxide and acetic anhydride.